Penetration Mechanism And Performance Of PE Laminates In Composite Armor

At present,the research and design of composite armor are mostly in the empirical,macroscopic and rough stage.The traditional composite armor design method mainly includes experimental method and numerical analysis method.However,the previous numerical analysis methods are not accurate because of insufficient understanding of the dynamic constitutive equation of materials.In this paper,the author hopes to establish a new research method of composite armor and guide the accurate design of composite armor by studying the relationship between the damage characteristics of materials and their absorbed energy and taking the damage characteristics of materials as the criterion.This paper firstly studied the resistance performance and damage characteristics of ceramics-PE composite armor.Research showed that the composite armor damage energy dissipation could be divided into two parts including the interaction between the bullet and the target plate and the damage to the structure of the target plate.The typical damage characteristics of composite armor include the broken of ceramic plate,the deformation damage of PE plates and the breakage of the bullets.A large number of experimental results showed that there was a relationship between the damage characteristics of composite armor and the kinetic energy of bullets absorbed by composite armor,which provided the possibility of designing the armor efficiently.For this reason,the anti-penetration behavior and performance of PE back-plate in ceramic/PE composite armor were studied in the secend part of this paper.The antipenetration performance and failure mechanism of PE laminated plates are studied by means of experimental testing.Firstly,the penetration test of 1mm PE sheet was carried out with small steel balls.The penetration speed was 50 m/s ~ 800 m/s,and the different responses of PE sheet at different speeds were studied.After that,penetration tests were carried out on PE plates of 1 mm,3 mm and 5 mm with small steel balls to study the influence of PE plate thickness on the penetration resistance of PE plates.Then,three different shaped bullets(flat nose,semicircular nose and cone nose)were used to conduct penetration test on PE plate to study the impact of bullets of different shapes on the penetration performance of PE plate.High speed camera was carried out in the process of penetration test to observe the response of PE plates the in the process of projectile penetration,after the penetration test,the ultrasonic C-scan was used to detect internal damage of the samples,PE specimens were observed using scanning electron microscopy(SEM)to detect the damage forms.The damage form,energy absorption performance and damage mechanism of PE plate under impact load were analyzed.The tensile strength of PE fiber at different tensile speeds was tested as well to verify the previous results.The experimental results show that:1.With the increase of velocity,the kinetic energy of bullets absorbed by PE plate firstly increases,then remains stable,and then decreases.The maximum kinetic energy absorbed is 32.2 J.The breakdown speed of PE is about 280 m/s,and when the speed reaches about 300 m/s,the energy absorbed by PE plate will fluctuate greatly.When the impact velocity is between 300 m/s and 500 m/s,the energy absorbed by the PE plate is relatively stable,reaching about 26 J.As penetration speed continues to increase,the energy absorbed by PE plate shows a downward trend.2.PE fiber has obvious strain rate effect.In the range of tensile speed from 100 mm/min to 1000 mm/min,the fiber performance will gradually decrease.In addition,with the increase of tensile speed,namely the increase of strain rate,PE fiber has a tendency to change from toughness to rigidity.3.In the thickness effect test,with the increase of the thickness of PE plate,the energy absorbed by PE plate shows an exponential growth trend.The penetration resistance of PE sheet is greatly improved with the increase of its thickness.4.Under different projectile impact,the cone head projectile impact when PE board of ballistic limit minimum,the highest flat nose ballistic limit,at low speeds,the cone head projectile to PE board damage,the largest speed increased to three projectile can breakdown sheet,flat projectile of PE board has caused the most damage,and the flat head bullet penetration of PE board absorbed energy is the largest.